Lubricating oil



Patented Apr. 21, 1942 Lunmca'rme on.

No Drawing.

Our invention relates to methods for the production of lubricating oils and specifically comprises such products as new compositions of Applicationduly 10, 1940, Serial No. 344,734

14 Claims;

(01. sea-s) ing capacity, lubricants which may be used satisfactorily at higher temperatures of operation and lubricants more stable to the efiect of high temperatures and pressures under an oxidizing condition. The operating difiiculties encountered with Diesel engines now being used represent these increased demands and the increasing requirements being placed on lubricants. Other types of internal combustion engines encounter the same difiiculties in some duties and when employed for some services have encountered troubles similar toor identical with those occurring with Diesel engines.

Some of these difiiculties are sludge formation,

, sticking of piston rings and the like. The term sludge as used in this specification is used to indicate various types of materials which are objectionable and some of which preclude continuous normal operation. Others are objectionable only under abnormal operating conditions. Some of these sludge materials are objectionable under one set of certain operating conditions but not under another set of operating conditions. We do not limit our invention to any theory of the action of these sludges under various conditions. We do know thatlsome sludges are hard, adhesive, coherent and damaging to normal engine operation while others are soft, pliable, easily disintegrated and do not materially ailect normal engine operation. it

Probably the most serious damage is caused by that type of sludge which results in piston ring sticking. This in turn causes inadequate lubri cation of the piston and cylinder walls and hence increased cylinder wear. ing of the cylinder walls may occur and under severe conditions there may be actual seizure of the piston and cylinder by welding. Another consequence of ring sticking is blow-by which causes loss of power, increased consumption of fuel andlubricant for the same output and overheating of the piston and cylinder walls. Permanent distortion of the latter is a result of this overheating.

These difiiculties cannot be overcome by changing the character of the hydrocarbon oil itself. Minera1 lubricating oils of one type, however, maynot cause as much difiiculty as oils of another type. In some cases, changes in refining processes will reduce the difliculties to a certain extent, but it is commercially impractical and uneconomical to manufacture and distribute special lubricants from oil of a particular type and refined by a special and often expensive refining process. Generally speaking, the more highly paraflinic lubricants which are usually conceded to be superior lubricants are not as satisfactory as the naphthenic type lubricants for this specific purpose.

At least two special lubricants have been of fered to solve the foregoing difiiculties, but they have been found unsatisfactory and inadequate in many respects. One of these is a hydrocarbon lubricating oil to which has been added halogen bearing metal soaps while the other is a blend of mineral oil with a small quantity of calcium soaps of aromatic substituted fatty acids. Both of these types of special lubricants have been found inadequate in the following respects:

1. solubility -Many of these addition agents are not sufliciently soluble in hydrocarbon oils to give stable solutions containing the requisite amount of additive material. This causes difficulty in the manufacture and distribution of Mild and severe scorthese lubricants. agent be reduced to that which will remain permanently in solution, it. is insufficient'toproduce an appreciable improvement in the behavior of the oil even in normal use, This difliculty is sometimes partially overcome by the addition of a mutual solvent for both the soap and the'hydrocarbon oil.

2. To overcome this lack of solubility, free organic acids such as oleic, phenylstearic and the like may be added which increase the solubility of the soap in the oil, The added acid may be\ If the amount of addition the same or different from the acid combined as soap. The addition of free acid to lubricants, however, precludes their use With'many of the now common bearing metals especially those containing lead and cadmium because of the rapid corrosion of these metals by organic acids.

3. Efiectiveness-Neither of the two types of additive materials has satisfactorily reduced the ring sticking difiiculty. This failure may be due to lack of stability or lack of solubility in sufiicient amounts to accomplish the purpose or both.

One object of our invention is to provide lubricants which will greatly reduce or substantially eliminate ring sticking in internal combustion engines, particularly those of the Diesel type.

Another object of our invention is ,to provide materials which when added to hydrocarbon oils will accomplish the same result.

A further object of our invention is to provide addition agents for lubricants which accomplish the above purposes and which are at the same time noncorrosive to the various metals encountered in internal combustion engines.

A still further object of our invention is to provide addition agents for lubricants which ac-.

complish the above purposes and which are at the same time stable under the conditions of use and which do not accelerate the formation of any objectionable type of sludge.

Still another object of our invention is to provide addition agents for lubricants which will cause any sludge resulting from changes of the mineral oil during use to be of a soft, pliable,

noncohesive and noncoherent type which will not interfere with normal operation.

Briefly, our invention consists of the addition to lubricants of small amounts, usually not over 5.0 per cent, and more often of from 0.5 to 2.0 per cent of certain metal salts or soaps of organic acids containing, in addition to the acid group, an esterified hydroxyl grouping in the molecule. Most of the salts or soaps of the suitable metals with acids of the type described, namely, acids having an esterified hydroxyl group in the molecule, are characterized by their ready solubility in mineral oils. This is a distinct adtor oil, lard oil, shale oil, corn oil, cottonseed oil and the like.

The addition of organic acids to improve the solubility of metal soaps as disclosed inthe prior art is not nearly as effective as we obtain by introducing an esterified hydroxyl group or groups into the molecule itself. It is a distinct improvement to have a soluble soap with the solubilizing agent a nonacidic group in the molecule of the soaps depending on the valence of the metal. For

vantage in that blending of the additive agent with hydrocarbon oils is particularly easily accomplished and also in that there is minimized possibility of any separation of the added salt power for these salts than others though the greater solubility obtained by changing the base oil is still small compared to the introduction of an ester group into the soap radical. In general, naphth'enic base oils are better salt solvents than mixed 'or'p'araffin base oils of the same viscosity.

By oil having lubricating characteristics in the appended claims, we mean to include the socalled mineral .oils and various hydrogenated,

polymerized and otherwise synthetically treated oils such as voltolized oils and the like. Furthermore, the lubricating oil may consist in whole or in partof animal or vegetable oils such as casexample, we may use stannous or stannic salts. The salts of the same metal in different valence states are often quite different in solubility and su tabil y for special purposes. Thus salts of stannic tin appear to be better oxidation inhibitors than the corresponding stannous soaps. Plumbic lead soaps are more effective anti-knock agents when added to gasoline than the divalent lead soaps.

Some of these metals form salts or soaps which are more suitable than others for some purposes. Thus iron, lead, and copper soaps in general are found to be accelerators of oxidation in crankcase lubricants. Wh these are effective in reducing ring sticking, their other effect of accelerating oxidation renders them somewhat less desirable than other metal soaps in this particular service. On the other hand, the soluble lead soaps, for example, are quite desirable in the manufacture of mild and violent types of hypoid lubricants. Here the value of the extreme pressure characteristics of the soap far overshadow its oxidation accelerating ability. This is especially the case when we use a refined oil relatively difilcult to oxidize or add an oxidation inhibiting material or both.

In some cases, we may use metal salts of our ester-acids 'inwhich the metal is present as a complex ion. Thus the cobalt and nickel ions (trivalent) form complexes with the diamines such as ethylene and propylene diamines which may be used for preparing our salts.

The ester-acids which we use to prepare our addition agents are, in general, hydroxy acids whose hydroxyl groups are esterified. These are characterized by the formula HO2C.R.O.CO.R', in which R is a divalent group and R is a monovalent group.

In general our invention comprises an oil of lubricating viscosity containing in combination a small amount of one or several of the metal salts of the hydroxyacids whose hydroxyl groups are esterified.

The character of R and R in the above general formula may vary within wide limits, since the solubilizing effect of the ester group is so powerful that it overcomes any difficult solubility effect of R and R. Even radicals commonly thought to be insoluble in hydrocarbon oils may in some cases be used. The products, however, in which R and R may be carbocyclic, heterocyclic or open chain and may or may not carry substituting groups such as nitrogen, halogens, sulfur, or phosphorus containing groups. It is to be understood that any of hese substituting groups may be inserted in any of the specific compounds mentioned. Some examples of the acids we may use in making our metal salts or soaps are:

A. Cyclic hydroxyacids 1. With aliphatic acids, e. g.:

a. Stearoyl salicylic acid:

(0) H02C.C6H40.C0.C17H35 b. Trimyristoyl pyrogallic acid:

(1)HO2C.C6H2(O-CO.C15H31)3(3,4,5) 2. With cyclic acids, e. g.:

a. Furoyl mandelic acid:

HOzC.CHCsHs.O.C0.CrH3O b. Hydrocinnamoyl salicylic acid (0) H02C.C6H4.0.CO-CHZCH2C6H5 B. Aliphatic hydroxyacids 1. With aliphatic acids, e. g.:

a. Trimolecular self-condensation product of 12-hydroxystearic acid, trishydroxystearic acid HOzC(CH2)1oCH.CaH1s' O.CO(CH2)1oCH.CeH1a .cowmmcnonotna b. Tetramolecular self-c o n d e n s a t i o n product of 12-hydroxystearic acid, tetrakis-hydroxystearic acid 1102C (CH2)1DCH.CBH1S O.C O(CH2)10CH.CH;3

0.0 0 (CH2)10CHOHCBH|3 c. Stearoyl 12-hydroxystearic acid HOzC (CH2) nCH.CaH s C O.C17Has 2. With cyclic acids, e. g.:

a. Monophthalyl amyl lactate (o)H0,C.C H C0.0.CH(CH;) c0 0 b. Monophthalyl amyl citrate omo dc mcooc c. Diphthalyl amyl tartrate H020 (CH2)1oCH.CuH 3 .COCaHa e. Monoterephthalyl p-chloroethylmalate v Some examples of the metal salts or soaps which we prepare from these acids and blend with hydrocarbon oils to obtain our improved lubricants are:

The-'quantities of our metal salts or soaps to be used may vary within wide limits depending on their relative efiectiveness in accomplishing a certain-desired result. As oxidation inhibitors in crankcase oils from 0.01 to 1.0 per cent are generally effective. A blend of this composition has some beneficial effect on ring sticking as compared with a hydrocarbon oil, but in order toobtain a suflicient effect to be satisfactory more is usually required. Thus we may employ from 0.5 to 10 per cent in order to prevent ring stick- It is obvious that this will vary depending on the ring sticking tendency of the base oil, the efiiciency of the addition agent, temperature and other conditions of operation and the like.

We do not wish to limit ourselves to a blend of hydrocarbon oil and a single metal soap as we may use more than one soap in the same blend. These mixed soaps may be heterogeneous with respect to the acid or metal or both. Thus we may use a blend of hydrocarbon oil, a small quantity of tin cetyl phthalate and a small quantity of calcium cetyl phthalate. In this case the mixed soaps are heterogeneous with respect to metals. Another blend maycontainbesides the hydrocarbon oil small quantities of nickel octadecyl phthalate and nickel stearoyl-l2-hydroxystearic acid. This blend is heterogeneous with respect to acid radicals in the soaps. One blend consists of hydrocarbon oil, stannic cetyl 3-isopropyl G-methyl 3, 6 endoethylene-A -tetrahydrophthalic anhydride, calcium stearoyl salicylate and lead (11) amyl 3-isopropyl-6-methyl-3, 6-endoethylene-4-tetrahydrophthalic anhydride. This blend is heterogeneous with respect to both acids and metals.

Our metal soaps may be used advantageously in combination with lubricants of all kinds including those designed for use in automotive crankcases, Diesel oils, and any other oils of lubricating viscosity. Furthermore our addends are advantageously blended in gasoline and other petroleum fuels either directlyor after being blended first in a lubricating oil and then added to the fuel. Soap thickened lubricants, that is greases, are modified by the incorporation of The ordivarying amounts of our metal soaps. nary soaps used in making greases may be replaced in whole or in only small part by certain of our metal soaps. These addends modify considerably the tackiness, penetration, resistance to breakdown by working orheat, and other properties of the greases. In making these greases, the usual soaps such as sodium stearate, aluminum stearate, calcium soaps of beta fat and the like may be used to form the large part of the necessary soap. Various other thickening ingredients or materials for other purposes may be added. These include yarn, hair, graphite, glycerol, water, lamp black, mica, zinc dust, etc.

It may be desirable to include in one and the same blend, in addition to the addends here described, other addends for specific purposes.

' Thus we may add a pour point depressor such as a naphthalene-chlor-wax condensation product and a viscosity index improver such as certain resins or polymerized hydrocarbons in addition to our metal soaps of ester-acids. Furthermore, various other metallic compounds may be added to the blend without interfering with the action of our ingredients. Indeed, in some cases, it is advantageous to combine with our addends here described in a lubricating oil blend, such materials as calcium dichlorostearate, chromium oleate, aluminum stearate and other metallic soaps. We may also add various halogenated. oxygen-bearing ring or chain compounds including methyl dlchlorostearate, lauryl trichloroacetal, chlorodiphenylene oxide, chlorodiphenyl ether and the like. Furthermore, sulfur-bearing materials may be added in the form of sulfurized methyl esters of corn -oil acids, benzyl di'sulfide, alkyl polysulfides and the like.

It will be understood that certain features and subcombinationsare of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in details within the scope of our claims without departing from the spirit of our invention. is, therefore, to be understood that our invention is not to be limited to the specific details I shown and described.

Having thus described our invention, we claim:

1. A lubricant comprising in combination a major proportion of an oil having lubricating characteristics and a minor proportion of a metal salt of a hydroxy acid whose hydroxyl group is esterified.

2. A lubricant comprising in combinationa major proportion of an oil having lubricating characteristics and a minor proportion of a metal salt of an aliphatic hydroxy acid whose hydroxyl groupis esterified.

3. A lubricant comprising in combination a major proportion of an oil having lubricating characteristics and a minor proportion of a metal salt of a cyclic hydroxy acid whose hydroxyl group is esterified.

'4. A lubricant comprising in combination a major proportion of an oil having lubricating characteristics and a minor proportion of a metal salt of a hydroxy acid whose hydroxyl group is esterified by means of an aliphatic acid.

5. A lubricant comprising in combination a major proportion of an oil having lubricating characteristics and a minor proportion of a metal salt of a hydroxy acid whose hydroxyl group is esterified by means of a cyclic acid.

6. A lubricant comprising in combination a major proportion of an oil having lubricating characteristics and a minor proportion of a metal salt or. an aliphatic hydroxy acid whose hydroxyl group is esterified by means of an aliphatic acid.

7. A lubricant comprising in combination a major proportion of an oil having lubricating characteristics and a minor proportion of a metal salt of an aliphatic hydroxy acid whose hydroxyl group is esterified by means of a cyclic acid.

8. A lubricant comprising in combination a major proportion of an oil having lubricating characteristics and a minor proportion of a metal salt of a cyclic hydroxy acid whose hydroxyl group is esterified by means of an aliphatic acid.

9. A lubricant comprising in combination a major proportion of an oil having lubricating characteristics and a minor proportion of a metal salt of a cyclic hydroxy acid whose hydroxyl group is esterified by means of a cyclic acid.

10. A lubricant comprising in combination an oil of lubricating characteristics and from 0.01 to 10 per cent of a metal salt of a hydroxy acid whose hydroxyl group has been esterifled.

111 A lubricant comprising in combination an oil having lubricating characteristics and from 0.1 to 5 per cent of a metal salt of a hydroxy acid whose hydroxyl group has been esterifled.

12. A lubricant comprising in combination a major proportion of an oil having lubricating characteristics and a minor proportion of calcium stearoyl salicylate.

13; A lubricant comprising in combination a major proportion of an oil having lubricating characteristics and a minor proportion of calcium benzoyl hydroxystearate.

14. A lubricant comprising in combination a major proportion 01' an oil having lubricating characteristics and a minor proportion of calcium tetrakis hydroxystearate.

GORDON D. BYRKIT. WALDO L. STEINER. BERT H. LINCOLN. 

